Recently standards and specifications for global telecommunication networks have begun to emerge. One of these is 3rd Generation Partnership Project (3GPP), which in the near future will likely replace such digital mobile networks used today as GSM, PDC and IS-95. A 3GPP network comprises a core network for switching, routing and management related functions. The 3GPP network further comprises radio access networks (RAN) for radio related functions. The 3GPP network further comprises user equipment, e.g. mobile stations. The core network further comprises a circuit switched domain for processing circuit switched traffic and a packet switched domain for processing packet switched traffic. For radio access networks, there are several possible ways of implementation. A GERAN (GSM EDGE Radio Access Network) utilizes EDGE (Enhanced Data Rates for GSM Evolution) as radio interface. An UTRAN (Universal Terrestrial Radio Access Network) utilizes WCDMA (Wideband Code Division Multiple Access) as radio interface. An IP-PAN is a radio access network utilizing Internet Protocol (IP) as a transport mechanism. An IP-RAN redefines the system architecture of a radio access network, when compared to an UTRAN or GERAN. E.g. most of the functions of a centralized controller (e.g. Radio Network Controller RNC or Base Station Controller BSC) are moved to base stations. In particular, radio protocol related functions are moved to base stations. However, an IP-RAN still conforms to an Iu interface of an UTRAN as well as to air interfaces of WCDMA, GSM and/or GERAN.
In the following a traffic flow refers to data corresponding to one or more simultaneous data connections. For example, data corresponding to an email message comprises a data connection. Data corresponding to a World Wide Web (WWW) browsing session comprises another data connection. When transmitted simultaneously to or from a given mobile station, these two data connections comprise a traffic flow. A data connection comprises two components, a user plane connection and a control plane connection. The control plane connection refers to elements necessary for controlling a data connection, such as signaling, whereas the user plane connection refers to the actual payload.
Traditionally telecommunication networks have been based on network elements which each process both the user plane and control plane connections of a data connection. Lately, however, network architectures have begun to emerge in which control and user plane connections are processed separately, e.g. by physically separate network elements. In the following such networks are referred to as being based on server-gateway architecture, in which context a server refers to a network element for processing control plane connections of traffic flows and a gateway refers to a network element for processing user plane connections of the same traffic flows. An example of such a server is a RAN Access Server (RNAS) used in IP-RAN for processing control plane connections between the IP-RAN and core network. An example of such a gateway is a RAN Gateway (RNGW) used in IP-RAN for processing user plane connections between the IP-RAN and core network. Another example of such a gateway is a Circuit Switched Gateway (CSGW) used in IP-RAN for processing user plane connections between the IP-RAN and A interface as well as between the IP-RAN and ATM-based Iu-CS-interface.
At the moment, however, there remains a significant problem with server-gateway architecture based telecommunication networks in that servers are not provided a recovery mechanism. Thus in case of a malfunctioning server, network users may experience service interruptions. Using mobility procedures implemented in prior art server-gateway interfaces it may be possible to change a malfunctioning gateway to a different available gateway. For servers, however, there are no such procedures. Hardware redundancy within a server is the only option to provide for high availability server operation at the moment. Unfortunately hardware redundancy leads to complexities in implementation and maintenance, thus resulting in unnecessarily high costs.
Thus there is an obvious need for a solution providing a server control plane connections recovery mechanism in a server-gateway architecture based telecommunication network.